This study aims to evaluate the impact of a multimodal intervention to improve hand hygiene amongst health care workers in accordance with the WHO Guidelines on Hand Hygiene in Health Care. The research design is a prospective stepped wedged trial using all in-patient wards in a 1,000 bed hospital located in Northeast Thailand (Sappasitthiprasong hospital, Ubon Ratchatani). A stepped wedge design is a type of cluster randomized controlled trial which is appropriate when there are prior reasons to believe the intervention will be beneficial (as opposed to equipoise) and when it is impractical to deliver the intervention to all study units simultaneously. Both conditions hold here. The intervention will include educational visits to healthcare workers, improved reminders in the workplace, audit and feedback and social marketing with the aim of inducing behavioural and cultural change in relation to hand hygiene. The intervention will be delivered by the infection control team and the infection control ward nurses (ICWNs) who will receive additional training. The primary outcome will be directly observed hand hygiene compliance. Secondary outcomes will include incidence density of hospital-associated bloodstream and urinary tract infections with specified multiply antibiotic resistant bacteria, incidence density of hospital-associated bloodstream and urinary tract infections with non-multiply antibiotic resistant bacteria, total patient mortality rates, and ward-based consumption of alcohol hand rub and soap (a proxy for hand hygiene compliance).